[llvm] [SCEV] Add PHI SCEV verification to ensure availability at loop entry (PR #127550)

[Aleksandr Popov via llvm-commits]

aleks-tmb wrote:

> Why doesn't the existing loop and block disposition verification catch this? isAvailableAtEntry is a combination of LoopInvariant and ProperlyDominatesBlock dispositions.

The motivating example can be found here: https://github.com/llvm/llvm-project/issues/127534. 
In this case, both LoopDispositions and BlockDispositions are empty

https://github.com/llvm/llvm-project/pull/127550